Swollen knee, or a knee that gives way: possible causes and what to do
Why a knee swells or gives way, what to do after a twist or injury, and which signs mean you should be seen promptly.
A knee can swell for many reasons, from a twist or knock to osteoarthritis or inflammation inside the joint. A knee that gives way, buckles or feels unstable can come from weakness around the joint, but can also point to a ligament or cartilage injury. The key point is how it started and what you can do on it.
When to get urgent help
Go to A&E or call 999 if you have any of these. They can be signs of a fracture, infection, blood clot or other emergency.
- A limb that looks deformed, or a joint that you cannot move or put weight on after an injury
- A cold, pale or numb foot or hand after injury
- A hot, red, swollen joint with a high temperature
- A painful, swollen, warm calf, with or without breathlessness or chest pain
What it can feel like
- Puffiness or swelling around the kneecap or all around the joint
- A knee that feels tight, stiff and hard to fully bend or straighten
- A sense of the knee giving way, buckling or not being trustworthy, particularly on stairs, turning or stepping off a kerb
- A pop at the time of a twist, followed by swelling over the next hours
Common contributors
- A sprain or strain of a ligament, or a tear of the meniscus (cartilage), after a twist, a knock or a landing from a jump
- Osteoarthritis, which can cause swelling after activity
- Overuse and irritation of the tissues around the kneecap
- Weak thigh and hip muscles, which can make a knee feel unstable
- Less often, inflammatory conditions, gout or infection, which usually come with heat, redness and feeling unwell
General self-care
These are general comfort measures many people find reasonable. They are not a treatment plan, and what suits one person may not suit another.
- For a recent sprain or strain, the NHS advises protecting the joint, avoiding heavy activity, applying an ice pack wrapped in a towel, and raising the leg when you can
- Keep gently moving the knee within comfort rather than keeping it completely still
- A supportive bandage can be comfortable for some people, but do not wrap it so tightly that it causes more swelling or tingling
- Return to sport only when the knee is not swollen, you can move it fully, and it feels stable. If it keeps giving way, get it assessed first
- If you use over-the-counter pain relief, follow the packet instructions or ask a pharmacist
When to see your GP
See your GP promptly, or call NHS 111, if you have any of the following:
- Pain after a significant injury, fall or twist
- Pain that is constant, severe or getting worse, or wakes you at night
- Unexplained weight loss, fever or feeling generally unwell with limb pain
Consider seeing your GP if:
- A knee that is severely swollen, very painful, or that you cannot put weight on. The NHS says to call NHS 111 or get urgent help
- A hot, red, swollen knee, especially with a fever. This needs same-day medical assessment
- A knee that locks, will not fully straighten, or repeatedly gives way after an injury
- Swelling behind the knee together with calf pain, swelling or warmth. This may be a clot. If you also feel breathless or have chest pain, call 999
Where an osteopath fits in
There is limited good-quality research showing that hands-on treatment changes the course of a swollen knee or one that gives way, so I do not claim that osteopathy treats it.
What an osteopath can usefully do is examine the knee, hip and ankle, test whether the ligaments and cartilage seem stable, decide whether you should be referred for imaging or a specialist opinion, and guide strengthening and a gradual return to activity once it is safe. A knee that is hot, locked or severely swollen needs medical assessment first. If the assessment suggests you need your GP, a physiotherapist or a specialist instead, I will tell you.
If you would like your symptoms assessed, you are welcome to book an appointment. Osteopathic care is not right for everyone, and if something needs medical attention first, I will tell you.
Common questions
Why is my knee swollen with no injury?
Common reasons include osteoarthritis, overuse and irritation around the kneecap. Less often, inflammation inside the joint, gout or infection are responsible. If the knee is hot, red or you feel unwell, see a doctor the same day.
Why does my knee give way?
Weak muscles around the knee and hip, pain, or an injury to a ligament or the cartilage can all make a knee feel unreliable. A knee that gives way repeatedly after a twisting injury should be assessed before you return to sport.
Should I rest a swollen knee?
The NHS advice for a recent sprain is to protect the joint, ice it wrapped in a towel and raise it, while gently moving it within comfort. Seek help if it is severely swollen, hot or you cannot bear weight.
Sources and further reading
Links open in a new tab. Sources were checked in October 2026.
Related guides
This page is general information to help you understand common aches and pains. It is not medical advice and cannot diagnose your problem. If you are worried about your symptoms, please speak to your GP or call NHS 111.